The Achterbahn Stream Cipher
Berndt M. Gammel, Rainer Göttfert, Oliver Kniffler · 2005
Contents 1 Introduction 3 1.1 Abriefdescriptionofthekeystreamgenerator............. 3 2 Preliminaries 4 3 Detailed description of the keystream generator 8 3.1 TheBooleancombiningfunction..................... 8 3.2 Thefeedbackshiftregisters ....................... 9 3.3 Thelinearfeedforwardfunctions..................... 11 3.4 Linearcomplexityandperiodofthekeystream............. 14 3.5 Thereducedkeystreamgenerator .................... 16 4 The key-loading algorithm 17 5 Security properties 20 6 Parallel implementation 21 7 Comparison of hardware designs 23 7.1 Areaandpower.............................. 23 7.2 Throughput ................................ 24 7.3 Implementatione#ciency ........................ 25 7.4 Scalability ................................. 25 7.5 Discussion................................. 25 8 Mathematical Background 29 9Conclusion 38 1 Introduction The proposed stream cipher Achterbahn is a binary additive stream cipher. In a binary additive stream ci